Systems and methods for sealing and providing wireless power to wearable or implantable devices

This application is a continuation of U.S. patent application Ser. No. 17/624,465 filed Jan. 3, 2022, which is a 371 application of PCT/US2020/040666 filed Jul. 2, 2020, which claims priority to U.S. Provisional Application No. 63/004,856 filed Apr. 3, 2020 and U.S. Provisional Application No. 62/870,136 filed Jul. 3, 2019, the entireties of which are hereby incorporated by reference for all purposes.

The present application generally relates to wearable devices and near-field wireless power transmission, and more specifically relates to systems and methods for sealing wearable electronic devices and dynamic control of near-field wireless power.

Wearable electronic devices may be used for a variety of reasons. For example, wristwatches, activity monitors, physiological sensors, etc. may be worn to provide information to the wearer or to sense characteristics of the wearer. Sensed information may be viewed by the wearer or may be transmitted to another device, such as the wearer's smartphone. Further, wearable or implantable electronic devices typically derive power from an on-board battery; however, it is also possible to wirelessly transmit power to such devices. Wireless power transmission may be used to power the electronic device or to charge an on-board battery. Such systems generate an electromagnetic coupling between an antenna in a charger device and an antenna in the target device to transfer power from the charger to the target device.

Various examples are described for sealing and providing wireless power to wearable or implantable devices. One example device includes a first housing portion defining a first coupling surface; a second housing portion defining a second coupling surface, the first housing portion coupled to the second housing portion to form a housing, the first housing portion and the second housing portion defining an opening, the opening intersecting the first coupling surface and the second coupling surface; a first gasket positioned between the first coupling surface and the second coupling surface, the first gasket providing a first seal between the first housing portion and the second housing portion, a printed circuit board (“PCB”) disposed within the housing and coupled to at least one of the first or second housing portions; an electrical connector electrically coupled to the printed circuit board and positioned within the opening; and a second gasket positioned between the electrical connector and the housing, the second gasket providing a second seal between the electrical connector and the housing, wherein the first gasket is positioned to abut the second gasket and wherein compression of the first gasket between the first and second housing portions provides a third seal between the first gasket and the second gasket.

Another example device includes a first housing portion defining a first coupling surface; a second housing portion defining a second coupling surface, the first housing portion coupled to the second housing portion to form a housing, the first housing portion and the second housing portion defining an opening, the opening intersecting the first coupling surface and the second coupling surface; a printed circuit board (“PCB”) disposed within the housing and coupled to at least one of the first or second housing portions; an electrical connector electrically coupled to the printed circuit board and positioned within the opening; a gasket defined to correspond to the first and second coupling surfaces and to the electrical connector; and wherein: the gasket is positioned between the first coupling surface and the second coupling surface, the gasket providing a first seal between the first housing portion and the second housing portion, and the electrical connector is positioned to extend through the gasket, the gasket providing a second seal between the electrical connector and the housing.

One example method includes providing a first housing portion defining a first coupling surface; providing a second housing portion defining a second coupling surface, the first and second housing portions defining a housing when coupled, the housing defining an opening, the opening intersecting the first coupling surface and the second coupling surface; physically coupling a first gasket to one of the first or second coupling surfaces; providing a printed circuit board (“PCB”) having an electrical connector; physically coupling a second gasket to the electrical connector; physically coupling the PCB to at least one of the first or second housing portions and engaging the second gasket with the at least one of the first or second housing portions; physically coupling the one of the first or second housing portions to the other of the first or second housing portions; applying a sealing force to the first and second housing portions to compress the first gasket to create a first seal; engaging the second gasket with the other of the first or second housing portions to create a second seal; and engaging the second gasket with the first gasket to create a third seal.

Another example method includes providing a first housing portion defining a first coupling surface; providing a second housing portion defining a second coupling surface, the first and second housing portions defining a housing when coupled, the housing defining an opening, the opening intersecting the first coupling surface and the second coupling surface; providing a printed circuit board (“PCB”) having an electrical connector; physically coupling the PCB to at least one of the first or second housing portions; physically coupling a gasket to one of the first or second coupling surfaces; engaging the gasket with the one of the first or second housing portions and the electrical connector; physically coupling the one of the first or second housing portions to the other of the first or second housing portions; and applying a sealing force to the first and second housing portions to compress the gasket to create a first seal, and where the electrical connector is positioned to extend through the gasket, the gasket providing a second seal between the electrical connector and the housing.

Another example device includes a wireless field driver comprising a first antenna coil and an electrical current source electrically coupled to the first antenna coil; an electromagnetic field (“EMF”) sensor comprising a second antenna coil, wherein the EMF sensor is configured to generate a sensor signal indicative of a signal strength from the first antenna coil; a non-transitory computer-readable medium; and a processor in communication with the non-transitory computer-readable medium, the processor configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: cause the electrical current source to output a current to the first antenna coil to generate a first EMF; estimate the signal strength of the first EMF based on the sensor signal; and adjust the current to the first antenna coil based on an estimated signal strength of the first EMF to maintain a power characteristic and generate a second EMF at the first antenna coil.

One example method includes causing an electrical current source of a wireless field driver of a wireless device to output a current to a first antenna coil to generate a first EMF; receiving one or more signals from an EMF sensor of the wireless device indicating a sensed strength of the first EMF, the EMF sensor comprising a second antenna coil; estimating a strength of the first EMF based on the one or more sensor signals; and adjusting the current based on the estimated strength of the first EMF to generate a second EMF at the first antenna coil.

One example non-transitory computer-readable medium comprises processor-executable instructions to cause a processor to cause an electrical current source of a wireless field driver of a wireless device to output a current to a first antenna coil to generate a first EMF; receive one or more signals from an electromagnetic field (“EMF”) sensor indicating a sensed strength of the first EMF, the EMF sensor comprising a second antenna coil; determine a strength of the first EMF based on the one or more signals; and adjust the current based on the sensed strength of the first EMF to generate a second EMF.

These illustrative examples are mentioned not to limit or define the scope of this disclosure, but rather to provide examples to aid understanding thereof. Illustrative examples are discussed in the Detailed Description, which provides further description. Advantages offered by various examples may be further understood by examining this specification.

Examples are described herein in the context of systems and methods for sealing and providing wireless power to wearable or implantable devices. Those of ordinary skill in the art will realize that the following description is illustrative only and is not intended to be in any way limiting. Reference will now be made in detail to implementations of examples as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following description to refer to the same or like items.

In the interest of clarity, not all of the routine features of the examples described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another.

Some electronic devices may be worn against the user's skin or on the user's body and may be subjected to many different types of materials that may damage or destroy sensitive electronics within the wearable device. Because wearable devices may have a relatively long useful life, e.g., multiple years, it is likely that the device will encounter many different environments. In addition, the user may occasionally clean the device, which may include rinsing the device under a faucet or wearing it into the shower or a bath. Thus, these devices may be sealed during assembly to prevent ingress of such materials, notably moisture.

An illustrative example of such a device has two halves of a mechanical housing that contain and protect the device's electronics. The two halves of the housing are pressed together and sealed during manufacture to protect the electronics. The seal in this example is a gasket that matches the perimeters of the two halves of the housing and sits between the two housing halves when they are fastened together, such as using screws or a pressure-sensitive adhesive (“PSA”). During this process, the gasket is compressed between the two housing halves and seals the assembled housing.

However, example wearable devices according to this disclosure may include one or more ports to enable cables or wires to be connected to the wearable device. In this example, the wearable device has an electrical charging port to enable a charging cable to be connected to the device to charge the device's battery. Thus, the perimeter of the assembled housing is interrupted by an opening to accommodate the charging port. The opening in this example is oriented perpendicularly to the gasket that seals the two housing halves, and thus, the gasket cannot seal the entire perimeter of the housing.

Instead, this opening is sealed with a second gasket that is pressed against the connector assembly that is positioned within the opening. The connector assembly includes a connector cover and an electrical connector. The electrical connector provides the connection point for a charging cable, and is also electrically connected to a printed circuit board (“PCB”) mounted to one of the two halves of the housing. To compress the second gasket, the second gasket is positioned between the connector cover and the housing. The PCB is biased against the outer edge of the housing, which in turn presses the connector cover against the housing. The PCB is then securely attached to one of the housing halves to maintain the biasing force. The main or “perimeter” gasket, discussed above, is then compressed between the two housing halves and against the second or “opening” gasket to both seal the housing halves and to form a seal at the interface of the two gaskets. Thus, two gaskets together provide a complete seal to prevent moisture and contaminant ingress into the wearable device.

This example device employs a connector opening that straddles the joint between the two housing halves, thereby creating a need to seal the housing halves together as well as simultaneously seal the connector opening. However, because the planes in which the seals lie are orthogonal to each other, it creates a problem in that the perimeter gasket used to seal the two housing halves together cannot extend through the opening and thus cannot seal the opening. In addition, because the two different gaskets interface, ensuring a tight seal between the two gaskets must be accomplished by compressive forces on each gasket. An advantage of using gaskets to seal the two housing portions and the electrical connector, rather than welding or otherwise fusing the two housing portions together to seal the wearable device, is that the device may be re-opened to fix or replace components, such as a battery, and then re-sealed. Further, manufacturing and assembly processes may be simplified by using gaskets rather than more complex processes, such as welding, epoxying, or otherwise fusing the two halves together.

To power or charge an implanted electronic device, a user may bring a charger device within proximity of the implanted device and activate the charging functionality, such as by pressing a button or interacting with a touch screen. The charger device then activates a power amplifier and sends an alternating current having a predetermined frequency through a transmit antenna coil to generate an alternating electromagnetic field (“EMF”). A corresponding receive antenna coil in the implanted device couples with the EMF and obtains electromagnetic (“EM”) energy from the field, which it then uses to power various electronic components or to charge its battery.

However, the power received by the implanted device may vary based on the strength of the EMF or the quality of the coupling with the EMF, which may change based on the relative positioning of the antenna coils, e.g., the alignment of the antenna coils or the distance between the coils. Thus, the amount of power received by the implant device may vary. In addition, if the target device is not able to send feedback information to the charger device, the charge device still needs to ensure that an appropriate amount of EMF is transmitted. In this example, to help the charger device output an EMF with a target power level, the charger device includes an integrated EMF sensor.

The EMF sensor in this example includes a second antennal coil that is aligned coaxially with the transmit antenna coil. This second coil also electromagnetically couples with the EMF and outputs a signal based on the strength of the EMF. The signal from the second antenna coil is sent both to a peak detector and to a phase detector. The peak detector receives the signal and outputs a DC value indicating the peak voltage (or current) output by the second antennal coil. The phase detector receives the signal from the second antenna coil and outputs a phase change based on a reference signal.

The peak voltage (or current) signal and the phase change signal are both transmitted to a microcontroller, which receives the signals and determines the strength of the EMF based on the peak voltage (or current) signal. The phase change signal is used to indicate the RF load impedance or to receive near-field communications from the target device, e.g., an amount of power received from the EMF by the target device. Based on the estimated EMF strength and a target EMF strength, the microcontroller executes a proportional-integral-derivative (“PID”) feedback control loop to adjust the amount of current output by the power amplifier to achieve the target EMF strength. Thus, the charger device may be able to dynamically adjust the strength of the generated EMF in real-time or near-real time to provide the power needed by the target device.

In addition to estimating the EMF strength and obtaining RF load information, such an EMF sensor can enable other functionality, such as foreign object detection, power amplifier tuning to improve efficiency, and mitigation of electromagnetic interference (“EMI”). For example, the receive antenna coil in a target device typically introduces harmonic oscillations into the generated EMF, whereas an interfering foreign object typically will not. Thus, by filtering the signal received from the EMF sensor to identify harmonics, or by identifying a lack of such harmonics, foreign objects may be detected. Alternatively, foreign objects may be detected instead (or in addition) based on a determined RF load impedance exceeding a threshold impedance. In addition, EMI mitigation may be employed based on the magnitude of the sensed harmonics. Such harmonics typically correlate with EMI, and so if the magnitude of one or more sensed harmonics exceeds a threshold, the EMF strength may be reduced to reduce potential EMI effects.

Further, power amplifier efficiency may also be improved by adjusting a duty cycle of the power amplifier based on the detected EMF. To do so, the the transmit current is held constant, the duty cycle is varied, and the power usage at each tested duty cycle is determined. A duty cycle may then be selected by identifying the lowest calculated power usage across the tested duty cycles.

Thus, such an example charger may be able to adjust its own power output in real-time to ensure an appropriate amount of energy is output to a target device. Further, such techniques enable the use of less sophisticated target devices, such as target devices that lack separate communications capability, e.g., by omitting Bluetooth (“BT”) or BT low-energy (“BLE”) components. In addition, still other advantages, such as foreign object detection, load impedance detection and power amplifier tuning, and EMI mitigation, may be realized according to some examples.

These illustrative examples are given to introduce the reader to the general subject matter discussed herein and the disclosure is not limited to this example. The following sections describe various additional non-limiting examples and examples of systems and methods for sealing and providing wireless power to wearable or implantable devices.

1 1 FIGS.A-B 1 1 FIGS.A-B 100 100 100 Referring now to,show an example wearable electronic device. The devicemay be any suitable electronic device and may provide any of a variety of functionalities to the user. For example, the devicein this example is used to wirelessly charge or otherwise wirelessly supply power to implanted devices within the wearer; however, other types of wearable devices may include sensors, such as pulse monitors, accelerometers, electrocardiogram electrodes, etc., or may be user devices such as a smartwatch, a personal communication device (e.g., an emergency communications device for elderly users), headphones, earbuds, etc.

Because the device is intended to be worn by a user and to be used over an extended period of time, e.g., weeks, months, or years, it will be subjected to various environmental conditions that might damage the electronic components within the device, such as moisture or running water. To prevent such damage, the device is sealed to prevent moisture ingress.

100 110 112 110 112 120 100 100 As can be seen, the wearable devicehas a housing that is made by coupling and sealing two housing portions,together. In this example, the device is generally disc-shaped with two housing portions,that seal along a circular perimeter. It should be appreciated that any suitable device shape may be used, however. This perimeter is interrupted by an opening with an electrical connectorthat can be used to connect an external device, such as an electric charger or a computing device, to charge the deviceor to communicate with the device.

120 110 112 110 112 100 100 Because the device's housing includes an electrical connectorthat interrupts the interface between the housing portions,, a simple circumferential seal between the two housing portions,will not entirely seal the device. Further, because the wearable device is intended to be used for a period of weeks, months, or years, it may need to be repaired or have components replaced, such as a battery, and so the device may need to be opened. As a result, a permanent seal, such as a weld or epoxy adhesive, may not be desirable. Instead, as will be discussed in more detail below, the deviceis sealed by one or more gaskets.

2 2 FIGS.A-B 2 FIG.A 200 200 200 213 220 220 200 220 Referring now to,shows an exploded view of an example wearable device. The devicein this example is a wearable wireless charging and power-delivery device suitable for use with one or more implanted device, such as neurostimulators. The deviceincludes a PCBwith relevant electronics, such as a processor (e.g., a microcontroller), an RF transceiver, and an electrical connector. In this example, the electrical connector is a universal serial bus (“USB”) C-type connector (“USB-C”), but may be any suitable electrical connector in various examples. For example, the electrical connectormay be any suitable USB-style connector, a power connector (e.g., connectable to a wall charger), a 3.5 mm headphone jack, etc. Further, while this example deviceonly includes one electrical connector, other example devices may include multiple electrical connectors.

213 212 213 In this example, the PCBsits atop and is physically coupled, e.g., by a PSA, to a foam pad, which in turn is physically coupled to a housing portion. A coil antenna is positioned around the PCBand is electrically connected to the RF transceiver when assembled.

100 200 210 212 100 200 220 210 212 214 216 210 212 210 212 214 216 210 212 214 216 210 212 214 216 220 1 1 FIGS.A-B 1 1 FIGS.A-B As with the deviceshown in, this example deviceincludes two housing portions,that together form a housing for the device. Further, and similar to the deviceof, this deviceincludes an electrical connectorthat interrupts an interface between the two housing portions,at an opening created by two partial openings,, one defined in each of the two housing portions,. The opening is partially formed in each of the housing portions,by the respective partial openings,formed in the respective housing portions,. The opening is then formed when the partial openings,are aligned and the housing portions,are joined together. It should be appreciated that the size and shape of the opening (and consequently the partial openings,) correspond to the type of electrical connectoremployed in this example. Thus, in other examples, the opening may have a different size or shape. Further, in examples with multiple electrical connectors, there may be multiple openings formed in the device housing to accommodate each of the electrical connectors, though in some examples, multiple electrical connectors may share a single opening.

200 230 232 230 210 212 210 212 a a To seal the deviceagainst moisture ingress, two gaskets,are employed. Gasketis formed from a foam material in a shape corresponding to the perimeter shape of the two housing portions,. The foam material has PSA applied to each side to adhere the gasket to a coupling surface,formed on each of the upper and lower housing portions. The gasket material may be supplied as a foam tape or may be cut from a foam pad or other suitable substrate. Further, while foam is employed as a gasket material in this example, any suitable gasket material may be employed, including compressible plastics.

210 210 210 212 212 230 210 212 210 212 210 212 210 212 a a a a a a In this example, the coupling surfaceon one housing portionprotrudes from the housing portion, while the other coupling surfaceis recessed within the other housing portion. The gasketmay then be placed against one of these coupling surfaces,and held in place by the PSA until it is pressed against the other coupling surface,when the two housing portions,are joined and a then compressive force (the “sealing force”) is applied to compress the gasket between the two housing portions,to provide a seal.

2 FIG.A 230 220 232 220 220 220 220 220 232 200 232 220 220 220 222 232 230 222 200 a a a a As can be seen in, gaskethas a gap in it corresponding to the opening formed in the housing to accommodate the electrical connector. Consequently, a second gasketis employed to seal the electrical connectoragainst the housing. In this example, the electrical connectorhas a portion that has been electrically coupled to the PCB, e.g., by soldering, and also includes a platethat is physically coupled to the electrical connector, though in this exploded view, it is shown separately. The electrical connector plateprovides a substantially flat coupling surface to which gasketmay be affixed prior to assembly of the device. Once the gasketis affixed to the electrical connector plate, it may be pressed against the housing or another surface coupled to the housing to create a seal around the electrical connectorand the opening, while the electrical connector plateis sealed against the electrical connector by a gasket integral to the electrical connector. In this example, a connector coveris positioned within the opening and pressed against the gasketto provide a seal. The gasket is thus pressed against interior surfaces of the housing, gasket(as will be described in more detail below), and the connector coverto seal the opening and to complete the seal of the device.

232 230 200 230 232 230 200 230 232 6 6 FIGS.A-C As mentioned above, gasketinterfaces with gasketto provide a complete seal for the device. Because gaskethas a gap corresponding to the opening, though with some small overlap to provide surfaces to engage with gasket, it does not seal the opening. Further, the opening is perpendicular to the plane of the gasket(or oblique to the plane at a different angle in some examples), complicating a seal of the entire device. To effect a complete seal, gasketis pressed against and engages with gasket, as will be shown in more detail with respect to.

232 220 213 212 213 220 232 232 a a In this example, gasketis applied to the electrical connector plateas discussed above and then the PCBis positioned in the housing portionon the foam pad assembly discussed above (it should be appreciated that the foam pad assembly is not required in some examples). The PCBis then biased by an external force, e.g., a person's finger or a robotically controlled tool, to press the electrical connector plateand gasketagainst the housing to help establish the seal between the gasketand the housing. In examples that employ a connector cover, it may be applied at this time or at a later time.

213 212 213 212 213 212 232 2 FIG.A While the PCBis biased as discussed above, it is securely coupled to the housing portionusing the screws depicted in. It should be appreciated that any suitable coupling technique may be employed according to different examples to couple the PCBto the housing portionwhile the biasing force is maintained. By coupling the PCBto the housing portionwhile the PCB is biased, the biasing of the gasket against the housing (or other surface) may be maintained even after the initial external biasing force is removed. The maintained biasing force may then help maintain the seal between the gasketand the opening. In addition, or instead of, the biasing force, additional material, such as a potting compound, may be applied around the perimeter of the opening or the electrical connector to further enhance the seal of the opening.

213 210 212 230 210 212 230 200 230 232 200 a a 2 FIG.A Once the PCB(and other internal components) are installed within the housing portion(s),, gasketmay be applied to one of the coupling surfaces,and the two housing portions may be pressed together and physically coupled using the screws depicted in(or any other suitable coupling technique. The force applied by the screws may provide the sealing force to compress the gasketand create a seal around the perimeter of the device. Further, compressing the gasketalso presses it against gasket, thereby completing the seal for the device. Thus, the device employs two gaskets oriented orthogonally to each other and engaged with each other to form a complete seal for the device against moisture or other contaminant ingress.

2 2 FIGS.A-B 2 2 FIGS.A-B 3 FIG. 2 2 FIGS.A-B 200 200 300 310 320 320 200 It should be appreciated that the specific sizes and shapes of the components inare examples of one device. Other examples according to this disclosure may have different housing shapes and profiles. For example, while a wearable wireless charging devices is shown in, the device may be shaped or configured as a wristwatch, a continuous glucose monitor (“CGM”) or other wearable biosensor, an insulin pump, a smartphone or tablet device, etc. Further, while the devicehas a circular disc-shaped housing, other example devices may have other housing cross-sections, such as square, rectangular, triangular, etc., and may thus use gaskets corresponding to the shapes of such housings. For example,shows an example smartphonehaving a housing made from two housing portions,having a rectangular shape while providing an opening to accommodate an electrical connector, similar to the deviceshown in.

220 230 210 212 230 400 410 412 430 432 430 420 4 FIG. 2 2 3 FIGS.A-B and 5 FIG. In addition, while the electrical connectoris positioned through an opening oriented substantially orthogonally to the gasketsealing the housing portions,, orthogonality is not required. Instead, the opening may be defined at any angle oblique to the gasketthat may be appropriate for a particular implementation. For example,shows a cross-section of a devicewith a housing formed by two housing portions,sealed by a gasketthat engages with another gasketthat seals an opening oriented at an oblique angle to gasket. Similar to the devices shown in, the opening provides access to an electrical connector. Further, some examples may have multiple openings, each of which may be sealed by a corresponding gasket that engages with a gasket sealing two housing portions of a device. For example,illustrates a smartwatch device having two openings to support two different electrical connectors, such as an electrical charger and a 3.5 mm headphone jack. Still further configurations may be employed in other examples according to this disclosure.

6 6 FIGS.A-C 6 6 FIGS.A-C 6 FIG.A 6 FIG.A 6 6 FIGS.B-C 600 620 600 630 632 620 622 632 630 612 600 632 630 630 632 a b a b Referring now to,show cut-away views of an electronic devicehaving an opening to accommodate an electrical connector.shows a cross-section of the deviceand illustrates to engagement of a perimeter gasketfor the device and the electrical connector gasket. As is shown in, as well as, the electrical connectoris sealed against a connector coverby gasket. The perimeter gasketis shaped to correspond to a coupling surface defined by the housing portionand includes a portion that deviates from the circular shape of the deviceto instead correspond to the edge of the opening and to engage with gasket, labelled as tabs-. These tabs-are integrally formed as a part of the gasket, but are shaped as shown to enable engagement with gasketand the opening in the housing.

630 620 620 626 620 630 630 630 632 630 632 630 626 a b a b In addition, the gasket tabs-are sized to engage with the electrical connectoritself. For example, the electrical connectorin this example has an O-ringthat runs around the perimeter of the electrical connectorto enable sealing of the electrical connector itself. The shape of the tabs-enable the gasketto engage with the O-ring to provide a further seal. Thus, the device has a first seal created by gasketbetween the housing portions of the device, a second seal created by gasketaround the opening, a third seal between gasketand, and a fourth seal between gasketand the O-ring. The creation of these multiple seals may help to further seal the device against moisture (or other contaminant) ingress.

7 7 FIGS.A-B 700 730 700 710 720 720 show another example deviceaccording to this disclosure. In this example, however, rather than using two different gaskets, the device is sealed by a single gasket. Similar to some other example devices according to this disclosure, the devicehas a housing formed from two housing portions,that are coupled together. In addition, the housing forms an opening to enable access to an electrical connector.

730 710 712 710 712 710 712 730 710 712 730 730 730 730 710 712 730 710 712 730 730 730 230 232 730 730 700 7 FIG.B a b a b As described above, a gasketis positioned between the two housing portions,to engage with sealing surfaces formed on each housing portion,. When the housing portions,are coupled together, they compress the gasket, forming a seal between the housing portions,. However, as shown in, the gasketis formed to have both a perimeter portionand an opening portion. The perimeter portionseals the housing portions,to each other, while the opening portionseals the housing portions,to the electrical connectorand seals the electrical connectorwithin the opening. Thus, gasketintegrates two gaskets, such as gasketsand, into a single gasket to seal the entire device. As with the gaskets discussed above, gasketmay be constructed from any suitable material, such as a foam material with a PSA applied to each side to assist with aligning the gasketwith the housing portions and sealing the device.

7 7 FIGS.A-B 730 The gasket shown inmay simplify the manufacturing process of some example devices since only a single gasket is needed. Thus, alignment and engagement of two different gaskets to each other is avoided. However, manufacturing of the gasketitself may be more complex.

8 8 FIGS.A-C 8 FIG.A 7 FIG.B 7 FIG.A 830 830 720 830 830 830 830 830 700 730 720 a b a b Referring now to,shows an example gasketusable for sealing wearable electronic devices according to this disclosure. In this example, similar to the example shown in, the gasketis constructed of a single piece of material suitable to seal both a housing portions to each other as well as sealing an electrical connector, e.g., electrical connector, to the housing. The gaskethas a perimeter portionand an opening portion. As with the example gaskets illustrated in the figures and as discussed above, the gasketis shaped to correspond to the perimeter shape of a wearable device. In this example, perimeter portionis shaped to correspond to the perimeter of the deviceshown in. The opening portionis shaped to correspond to the shape of the opening and to mate with the electrical connectorand the housing.

830 830 830 700 b a 8 FIG.C 4 FIG. In this example, the gasket is formed from a single piece of material, e.g., via laser cutting, stamping, etc., and is configured to be folded to create the opening portion. The fold is illustrated inwith the opening portion folded to be in a plane orthogonal to the plan of the perimeter portion. As discussed above, however, the relationship between the two gasket portions need not be orthogonal, but instead may have an oblique alignment, such as shown in. Further, in this example, the gasket material has a PSA applied to each side of the material, enabling the folded portions of the opening portionto seal to each other as well as adhere to and remain in place on the housing portions or against the electrical connector during assembly of the device. In some example, however, a PSA may be applied to the housing portions instead, or in addition to, the gasket itself. Such a technique is equally applicable to each of the example gaskets discussed herein.

830 8 8 FIGS.A-C 7 FIG.B Example gaskets according to the gasketshown inmay be advantageous as they may be relatively simply to form by cutting the gasket from a single sheet of material, rather than using a molding process, which may be needed for the example shown in.

700 730 830 730 830 730 7 7 8 8 FIGS.A-B andA-C 3 5 FIGS.- 7 7 8 8 FIGS.A-B andA-C 5 FIG. b As discussed above, while the example deviceand gaskets,shown inhave a particular shape and size, each may have any suitable size and shape, such as the sizes and shapes discussed above with respect to. Further, while the gaskets,shown ineach have only one opening portion, some examples may include multiple opening portions to accommodate multiple openings defined in a device housing, such as shown in.

9 FIG. 9 FIG. 2 2 FIGS.A-B 900 900 200 Referring now to,shows an example methodof sealing wearable electronic devices. The example methodwill be discussed with respect to the example deviceshown in; however, example methods according to this disclosure may be employed with respect to any suitable devices according to this disclosure.

910 210 212 210 212 210 210 212 213 210 212 230 232 3 5 FIGS.- 2 FIG.A At block, first and second housing portions,are obtained and provided for the assembly process. In this example, the housing portions,have circular shapes and together form a housing having a circular disc shape. However, it should be appreciated that any suitable housing shape may be employed, such as discussed above with respect to. Further, the device housing may be composed of multiple different components. For example, as can be seen in, the housing has a generally rectangular plate that is affixed to a cavity formed in housing portion. Such a plate may cover other openings in the housing, such as for a speaker or one or more light emitters, such as one or more light emitting diodes (“LEDs”). However, the housing portions,form the portion of the housing that protects the electronics positioned on the PCBin this example and are the housing portions,that are sealed by a perimeter gasketand an opening gasket, even if other gasket seals are used, such as to seal an opening for a speaker or one or more LEDs.

920 230 210 212 210 212 210 212 230 210 212 230 212 212 230 212 230 210 212 2 FIG.A a a a a a a At block, a gasketis coupled to one of the first or second housing portions. As discussed above with respect to, each housing portion,defines a coupling surface,. These coupling surface will interface and engage with each other when the housing portions,are coupled to each other. Thus, in this example, the gasketis coupled, e.g., using a PSA applied to the gasket material or to one of the coupling surfaces, to one of the coupling surfaces,. In some examples the gasketmay simply be laid in position on one of the coupling surfaces without the use of any adhesive or similar coupling mechanism. For example, coupling surfaceis recessed below the outer perimeter of the housing portionand thus, the gasketmay simply be laid on the recessed coupling surface, where it may stay in place within the recess. Still other approaches to positioning or coupling the gasketto one of the housing portions,may be employed.

930 232 220 220 213 220 220 232 220 200 a a a 2 FIG.A At block, a second gasketis coupled to an electrical connector plateof the electrical connector, which is electrically coupled to a PCBand is to be positioned within the housing. As shown in, the electrical connectorhas a connector platecoupled to it, and the gasketis coupled to the connector plateby way of a PSA applied to the gasket material. However, a PSA is not required. In some examples, the gasket may be pressed into place over an flange on the connector plate, which holds the gasket in place until the deviceis fully assembled.

940 213 210 212 213 214 216 232 210 212 220 232 213 212 212 220 620 626 620 626 620 620 a a 6 6 FIGS.A-C At block, the PCBis positioned within one of the housing portions,and a biasing force is applied to the PCBto press it towards the partial opening,, which may enable the gasketto engage with the housing portion,or to otherwise position the electrical connector plateand gasketin place to create a seal for the opening. In this example, the PCBis coupled to a foam pad by a PSA, and the foam pad is in turn coupled to the housing portionby another PSA. Once this assembly is in place within the housing portion, the biasing force is applied. It should be appreciated that a biasing force is not required in every example according to this disclosure. Instead, it may be employed in some examples to help provide a robust seal for the opening. However, in some examples, the position of the PCB and electrical connector platemay be sufficient to seal the opening without an additional biasing force. For example, as discussed above with respect to, the electrical connectormay include an O-ringthat encircles the outer perimeter of a portion of the electrical connector. This O-ringmay engage with the perimeter gasket, which may help seal the device. In such an example, a biasing force may not be needed as the opening gasket may seal the opening by engaging with the housing, while the O-ring may further supplement the seal provided by the opening gasket by engaging with the perimeter gasket. In addition, in some examples, an additional sealing material, such as a potting compound may be applied around the perimeter of the electrical connector to further seal the opening against moisture ingress.

950 213 213 213 213 213 212 213 213 At block, the PCBis physically coupled to the housing to hold it in place and, if a biasing force was applied, to maintain the biasing force. In an example where a biasing force is applied, this may deflect the foam pad the PCBis resting on. If the PCBis not coupled by an additional mechanism, the PCBmay return to an unbiased position when the biasing force is removed. Thus, in this example, screws are used to physically secure the PCBto the housing portion. The screws can then maintain the biasing force on the PCBand maintain the seal at the opening. If no biasing force is needed, a PSA may be sufficient to couple the PCBto the housing portion; however, screws or rivets or other coupling mechanisms may be employed as well.

960 210 212 230 At block, the two housing portions,are pressed together to apply a sealing force to the gasketand are coupled together, such as by using screw, rivets, etc.

970 232 210 212 213 230 213 210 230 212 222 970 210 212 At block, the opening gasketengages with the other housing portion,, e.g., the housing portion other than the one the PCBis coupled to, and also engages with the perimeter gasket, if it was not already engaged, e.g., the PCBwas affixed to one housing portion, while the perimeter gasketwas initially coupled to the other housing portion. Further, if an additional component is used to seal the opening, e.g., a connector cover, it is pressed into place within the opening to complete the seal of the opening. After performing the couplings and engagements discussed with respect to block, the seal between the two housing portions,is complete as is the seal of the electrical connector at the opening.

900 920 950 213 212 232 220 210 212 It should be appreciated that the ordering of the blocks in the example methodabove are not required and other orders may be employed. For example, blocks-may be performed in a different order, such as by first positioning the PCBwithin the housing portionand then applying the gasketto the electrical connector, and then applying the perimeter gasket to one of the housing portions,.

900 200 Further, it should be appreciated that this example methodmay not be sufficient to entirely assemble the device. Still other steps may be employed, such as to affix a cover plate, e.g., with a logo or product name, to the housing or to insert other components within the housing before it is sealed.

10 FIG. 10 FIG. 7 7 FIGS.A-B 1000 900 700 Referring now to,shows another example methodof sealing wearable electronic devices. The example methodwill be discussed with respect to the example deviceshown in; however, example methods according to this disclosure may be employed with respect to any suitable devices according to this disclosure.

1010 710 712 910 At block, first and second housing portions,are obtained and provided for the assembly process generally as discussed above with respect to block.

1020 730 920 730 730 730 710 712 b b At block, the gasketis coupled to one of the first or second housing portions generally as discussed above with respect to block. In this case, however, because the gasketincludes an opening portion, the opening portion of the gasketis positioned within the partial opening of the respective housing portion,.

1030 720 730 730 720 1030 1020 720 730 730 710 712 b At block, an electrical connectorelectrically coupled to a PCB an electrical connector cover, affixed to the electrical connector, is inserted within the opening portionof the gasket, which engages with the electrical connector, e.g., with the electrical connector plate portion of the electrical connector, generally as discussed above. It should be appreciated that blockmay be performed before blockto engage the electrical connectorwith the gasketbefore the gasketis positioned on one of the housing portions,.

1040 710 712 940 9 FIG. At block, a PCB is positioned within one of the housing portions,and a biasing force is applied to the PCB generally as discussed above with respect to block. However, similarly to the example discussed above with respect to, the biasing force need not be employed in some examples.

1050 710 712 950 At block, the PCB is physically coupled to one of the housing portions,generally as discussed above with respect to block.

1060 710 712 730 970 At block, the two housing portions,are pressed together to apply a sealing force to the gasketand are coupled together, generally as discussed above with respect to block.

11 11 FIGS.A-B 11 FIG.A 11 FIG. 1100 1110 1120 1110 1110 1110 1110 1120 1120 Referring now to,illustrates an example system for dynamic control of near-field wireless power. The systeminincludes two wireless devices,. Wireless devicewill be referred to as charger device, though this does not imply that the charger device(or any other “charger device” according to this disclosure) is only suitable for use as a battery charger. Rather, the charger deviceis capable of generating an EMF that may be used to provide electrical energy to another wireless device, which will be referred to as the target device.

11 FIG.A 1110 1112 1110 1112 1130 1120 1110 1120 1130 1120 1110 1120 1122 1130 1110 1114 1130 As can be seen in, the charger deviceincludes a transmit antenna coil. The charger devicetransmits current through the transmit antenna coilto generate an EMF. To supply power to the target device, the chargerdevice is brought into proximity to the target deviceand generates the EMF, which while depicted as being a signal transmitted to the target device, is actually a field surrounding the charger device. The target deviceis positioned within the field. The target device's receive antenna coilthen couples with the EMFto obtain electrical energy. In addition, the charger deviceemploys a second antenna coil—receive antenna coil—to also obtain energy from the EMF.

1114 1112 1114 1130 1112 1114 In this example, receive antenna coilis positioned concentrically to the transmit antenna coil. Such an arrangement may provide a more efficient coupling between the receive antenna coiland the EMF; however, it should be appreciated that the transmit and receive antenna coils,need not be arranged concentrically around a common axis.

11 FIG.B 11 FIG.B 1110 1112 1114 1112 1114 1112 1114 1115 1112 1114 1112 1114 Referring to,illustrates a cross-section of the charger deviceto show the arrangement of the transmit and receive antenna coils,. In this example, while the two antenna coils,are arranged concentrically, they are not co-planar. Specifically, in this example, the transmit antenna coilis positioned on one side a printed circuit board (“PCB”), while the receive antenna coilis positioned on the other side of the PCB, all of which are positioned within the wireless device's housing. Such an arrangement may be used due to positioning of other electronic components on the PCB. However, it should be appreciated that in some examples, the two antenna coils,may be co-planar. Further, whether the two antenna coils,, are arranged concentrically or not is independent of whether they are co-planar with respect to each other.

12 FIG. 12 FIG. 12 FIG. 1200 1200 1210 1212 1220 1222 1224 1220 1222 1224 1220 1230 Referring now to,shows an exploded view of an example charger devicefor dynamic control of near-field wireless power. The example charger deviceshown inincludes two housing portions, upper housingand lower housing. Positioned within the housing are a PCB, to which are coupled a transmit antenna coiland a receive antenna coilthat has been formed as a trace on the PCB. As can be seen, the transmit and receive antenna coils,are concentrically aligned, but are not co-planar. The PCBalso has several electronic components coupled to it, including a processor, a wireless field driver, and an EMF sensor. A batteryis included to provide power for the electronic components as well as to supply current to generate an EMF to transmit power to a target device.

13 FIG. 13 FIG. 1300 1300 1320 1330 1310 1320 1310 1320 1322 1324 Referring now to,illustrates an example wireless devicefor dynamic control of near-field wireless power. In this example, the charger deviceincludes a wireless field driverand an EMF sensor, both of which are connected to processor. The wireless field driveris configured to generate an EMF in response to a command from the processor. To do so, the wireless field driverincludes a current sourceand a transmit antenna coil.

1322 1324 1324 1120 15 17 FIGS.- 11 FIG.A In this example, the current sourceis a switching power amplifier, such as a high-efficiency switching amplifier. One example of such a switching power supply is discussed below with respect to. An advantage of using of such a power supply may include real-time adjustment of the power amplifier to reduce power consumption while maintaining a target EMF strength. However, it should be appreciated that any suitable variable alternating current (“AC”) power source may be employed to generate and transmit an alternating current to the transmit antenna coil. In response to such a current, the transmit antenna coilgenerates an alternating EMF that can be used to provide electrical power to a target device, e.g., target deviceshown in.

1330 1331 1320 1331 1333 1335 1333 1310 1310 1335 1337 1335 1339 1310 The EMF sensorin this example includes a receive antenna coilthat couples with the EMF generated by the wireless field driverand outputs an AC signal based on the strength of the field. The receive antenna coilis electrically coupled to a peak detectorand a zero-crossing detector. The output of the peak detectoris electrically coupled to the processorto provide signals to the processorindicating the magnitude of the EMF. The zero-crossing detectoris coupled to a phase detector, which receives the output from the zero-crossing detectorand a reference signalto detect a phase change in the EMF. The output of the phase detector is electrically coupled to the processorto transmit signals indicating phase information about the EMF.

1333 1214 With respect to the peak detector, any suitable peak detector may be employed. For example, a simple peak detector may be implemented by a diode in series with a capacitor coupled to the receive antenna coil. The voltage across the capacitor will then indicate the magnitude of the AC signal. However, more complex peak detectors may be employed depending on the application.

1335 1214 1335 1337 1339 1337 1337 1310 With respect to the zero-crossing detector, any suitable zero-crossing detector, such as commercially available semiconductor zero-crossing detector devices. Alternatively, a suitable electrical circuit may be used, such as a comparator coupled to the receive antenna coil. The output of the zero-crossing detectoris provided to the phase detector, which also receives a reference signal, e.g., based on the AC signal output by the current source. The phase detectorthen detects a phase difference between the output signal from the zero-crossing detector and the reference signal. The output of the phase detectorin this example is a voltage indicating the difference in phase between the zero-crossing detector signal and the reference signal, and is provided to the processorto indicate the phase change of the generated EMF.

1310 1310 1300 1300 The processorin this example is a microcontroller that executes processor-executable instructions stored in a memory (not shown) to receive the peak detector signals to estimate the strength of the EMF; however, it should be appreciated that any suitable processor may be employed, including application-specific integrated circuits (“ASIC”). The processoralso uses the phase detector signals to estimate the load impedance of the target device, to detect foreign objects located between the charger deviceand target device, or such objects in close proximity to the charger device. It may also determine potential harmful EMI effects and reduce the strength of the EMF accordingly.

1310 1310 1322 1310 14 FIG. In response to receiving the peak detector signal, the processorestimates the strength of the EMF and determines a difference between it and the target strength of the EMF. If the estimated strength is different than the target strength, the processoreither increases or decreases the amount of current output by the current sourceto adjust the strength of the EMF. By iteratively adjusting the current source's output current, the processoris able to adjust the strength of the EMF until it matches or is within a threshold amount of the target EMF strength. Example techniques for iteratively adjusting the output current are discussed below with respect to.

1310 1322 1300 In response to receiving the phase signal from the phase detector, the processorcan estimate a load impedance presented by the target wireless device. The estimated load impedance may be employed to tune adjust a duty cycle of the current sourceto better match the load impedance. Alternatively, or in addition, a target device may adjust its load impedance, e.g., by activating and deactivating electronic functionality, to communicate information to the charger device. For example, the target device may adjust its presented impedance to output data at a fixed bit rate, e.g., 1 bit per millisecond, which may be detected by changes in phase shifts detected by the phase detector. Such a data transmission technique may be used to provide information about the status of the target device, e.g., estimated received EMF strength, estimated power received, estimated power requirements, battery charge level, etc. Such information may then be employed to adjust the strength of the EMF.

1310 1300 For example, the processormay determine a difference between the estimated EMF strength determined by the charger deviceand the estimated EMF strength received from the target device. The difference may indicate a distance between the charger device and the target device and may be used to scale the target EMF strength based on the decrease in signal strength over distance according to an inverse-square relationship. In some examples, estimated power requirements received from the target device may be used to adjust a target EMF strength based on a difference between the estimated EMF strength determined by the charger device (or the target device) and the estimated power requirements.

14 FIG. 14 FIG. 13 FIG. 13 FIG. 1310 1400 1430 1400 1410 1440 1333 Referring now to,shows an example technique for dynamic control of near-field wireless power that may be employed by a processor of a charger device, e.g., the processorshown in. In this example, the technique employs a PID control systemto adjust an output current of a wireless field driver. The control systemaccepts a target EMF strengthas an input signal and the output of an EMF sensor, e.g., the output of the peak detectorof, as an error signal. The input and error signals are summed to obtain the error, which is provided to each of the P, I, and D portions of the PID controller. The outputs of these three blocks are summed to provide an adjusted control signal to the wireless field driver to adjust the amount of current output to the transmit antenna coil. The summation of these three terms may be represented by the following equation:

p i d Where the K, K, and Kterms represent coefficients for the P, I, and D terms, respectively, and the function e(t) represents the error signal over time. Adjusting the coefficients changes the response of the control system to the detected error, depending on the desired convergence time, allowable overshoot, etc. For example, a suitable transfer function may be designed based on desired pole and zero positions.

1400 1420 1420 1420 14 FIG. The techniqueshown inalso includes a saturation functionthat applies saturation limits to the output from the PID controller to limit the maximum output current or to limit the rate of change of the output current. For example, the saturation functionmay output a fixed saturation value if the output of the PID controller exceeds a threshold, e.g., if the PID controller outputs a signal indicating a current of 300 milliamps, while the current source is only capable of outputting a maximum of 100 milliamps, the saturation functionmay output a signal to cause the current source to output a current of 95 milliamps (or another value).

14 FIG. The PID controller shown inoperates iteratively over time to change the current output by the wireless field driver, thereby adjusting the strength of the EMF generated by a transmit antenna coil. Over successive iterations, the PID controller causes the estimated strength of the generated EMF to converge on the target EMF strength, provided the wireless field driver is capable of outputting a sufficiently strong EMF.

It should be appreciated that while this example employs a PID controller, one or two of the P, I, or D terms may be eliminated to provide a desired control system, e.g., a PI or a PD control system. Such alternative control system approaches may be suitable in different implementations, depending on system complexity or design requirements.

15 FIG. 15 FIG. 1 FIG. 1500 1510 1510 1 2 1520 1 2 1520 1 2 1 2 1520 1540 1550 1550 1560 7 1 1570 1520 1510 1 Referring now to,shows an example adjustable power amplifier suitable for use with example systems for dynamic control of near-field wireless power. The example systemincludes a DC/DC power supplywith selectable output voltage, as discussed above with respect to. It should be appreciated that any suitable DC power supply with an adjustable DC output voltage may be employed as the power supply, including adjustable AC/DC supplies. The power amplifier includes two MOSFETs M-Marranged as switches in a half-bridge configuration. The PWM gate driveris connected to the gates of each of the MOSFETs M-Mand toggles the gates to switch them on and off. The PWM gate drivermaintains the MOSFETs M-Min opposite states, such that Mhas the opposite state—on or off—as M, and operates them in a ZVS and ZCS mode. The PWM gate drivertoggles the switches according to a duty cycle selected by a controller (not shown) to provide an output signal to the tank circuit, which in combination with the low pass filter, provides the impedance transformation network. The output of the low-pass filteris provided to the load, which includes the transmit coil Land the receive coil and circuitry, represented by resistance R(R). The controllerprovides a duty cycle select signal to the PWM gate driverand provides a voltage select signal to the DC/DC converter.

1 2 1 2 1 2 1 2 1 2 In this example, each MOSFET M-Mhas a respective diode D-Dcoupled between its source and drain to circulate power through the respective MOSFET M-M, thereby allowing the power amplifier to accommodate a larger amount of load reactance. Schottky diodes, having low voltage drops, may be employed as D-Dto provide efficient circulation of energy, though other types of diodes may be employed according to some examples. Further, while the MOSFETs M-Mare operated substantially in a ZVS and ZCS mode, variations in load reactance may result in ZVS and ZCS conditions not being met across the entire range of load reactances, though such a configuration may still enable reduced power dissipation across the entire range of load reactances.

1540 1550 1530 1570 1520 The tank circuitis configured to operate in resonance at the desired transmission frequency, such as by providing substantially 0 ohms of resistance at resonance, or it may be employed to provide a predetermined impedance shift away from a resonant frequency. The filteris used to both provide low pass filtering of the power amplifier output, as well as to convert a range of load impedances to a predetermined range of impedances to present to the power amplifier. The range of load impedances may then be used by the controllerto select duty cycles for the PWM gate driver.

16 FIG. 16 FIG. 17 FIG. 15 FIG. 1600 1610 1610 1610 1550 1610 1510 1550 1610 1610 For example, referring to,shows a plotof duty cycles to achieve high efficiency at a target impedance within an impedance plane, where the x-axis represents resistance and the y-axis represents reactance. As can be seen, a curverepresents a correspondence between a duty cycle (normalized to a range from 0 to 1) and a load impedance. The points on the curverepresent the duty cycle for a particular impedance that provides optimal efficiency of power transfer from the power amplifier at that impedance. Deviation from the curve, such as due to limitations of the tank circuit and filter, may result in reduced efficiency in power transfer, however, as will be seen with respect to, close approximations to the curvemay still provide relatively efficient power transfer. The design of a circuit may affect the range of impedances within which the power supplycan efficiently transfer power to a target device. For example, the relatively simple impedance transformation network, including filtershown in, may closely approximate the curveover a small range of impedances before substantially deviating. More complex impedance transformation networks may be designed to allow a power supply to approximate the curveover a wider range of load impedances, though such impedance transformation networks may require more physical layout space.

1550 5 9 1610 3 1550 5 9 1710 1710 1610 1510 16 FIG. 17 FIG. 17 FIG. The filterin this example employs a capacitor Cand an inductor Land provides an approximation of the curveshown inover a range of load inductances as shown in. In this example, Chas a value of 26.3 nanofarads (“nF”) and the inductor has a value of 350 nanohenries (“nH”). The filteremploys a capacitor Cwith a value of 5.2 nF and an inductor Lwith a value of 94 nH. Using these circuit components, the power amplifier operates along approximation curvein. As can be seen, the approximation curveclosely approximates curveacross a range of load impedances of approximately 1 to 3 ohms before beginning to deviate. Thus, the power supplyis able to efficiently transfer power despite a 50% increase or decrease in load impedance from a midpoint load impedance of 2 ohms by varying a PWM duty cycle between 0.38 and 0.43.

15 FIG. 18 FIG. 18 FIG. 18 FIG. 1520 1570 1510 1810 1820 7 1810 1820 7 1510 1510 Referring again to, in addition to adjusting a duty cycle setting for the PWM gate driver, the controlleradjusts the power supplyoutput based on the PWM duty cycle. Referring to,shows two curves,representing current supplied to the transmit coil L(y-axis) by the power supply across a range of duty cycles (x-axis) at a particular voltage. In this example, the upper curverepresents the output at 10 volts, while the lower curverepresents the output at 5 volts. Thus, based on an amount of current to be supplied to the transmit coil L, the voltage output by the DC/DC converteris adjusted based on the duty cycle. In this example, a decrease in the duty cycle corresponds to an increase in the voltage output by the DC/DC converter. For example, to maintain a current of approximately 0.4 amps for change in the duty cycle from 0.43 to 0.39, the output of the DC/DC converter would increase from approximately 5 volts to approximately 10 volts. Thusrepresents a portion of a three-dimensional surface, where the x-axis represents duty cycle, the y-axis represents transmit coil current, and the z-axis represents DC/DC converter output voltage. Using such a surface, a combination of duty cycle and current can be employed to select a DC/DC converter output voltage. Thus, in some examples, the lookup table may be a two-dimensional array.

19 FIG. 19 FIG. 11 FIG.A 11 FIG.A 1900 1900 1910 1920 1910 1912 1914 1912 1914 1910 1912 1914 Referring now to,shows an example systemfor dynamic control of near-field wireless power. Similar to the example shown in, the systemincludes a charger deviceand a target device. The charger deviceincludes a transmit antenna coiland a receive antenna coil; however, unlike the example shown in, the two antenna coils,in the charger deviceare not concentrically aligned. In this example, they are co-planar; however, in some examples, they may not be in the same plane, e.g., they may be positioned on opposite sides of a PCB. Thus, different arrangements of the transmit and receive coils,may be used according to different examples.

20 FIG. 20 FIG. 11 FIG.A 2000 2010 2020 2020 2020 2010 2010 2020 Referring now to,shows another example systemfor dynamic control of near-field wireless power. In this example, the charger deviceand target deviceare similar to those shown in, however, each also includes a Bluetooth (“BT”) communications capabilities, e.g., BT low-energy (“BLE”). As discussed above, in some examples the target devicecan modify its apparent load impedance by activating and deactivating electronic components within the target device. By doing so, it can communicate information to the charger device, which will detect the changing load impedance as a change in phase of the generated EMF. In this example, however, the two devices,may instead communicate such feedback information via a BT or BLE connection.

2010 2030 2020 2020 2010 2010 2030 21 22 FIGS.- For example, the charger devicemay generate an EMFto provide electrical energy to the target device, which may use that energy to power various components of the device, including the BT or BLE subsystem. The two devices may then pair using the BT or BLE communications technique and the target devicemay transmit feedback information, e.g., estimated received EMF strength, estimated power received, estimated power requirements, etc., to the charger device. The charger devicemay then adjust the strength of the EMFbased on such information, such as described above and as will be described below with respect to.

21 FIG. 21 FIG. 13 14 FIGS.- 2100 2100 Referring now to,shows an example methodfor dynamic control of near-field wireless power. This example methodwill be described with respect to the example device and technique shown in. However, any suitable system, device, or technique according to this disclosure may be employed.

2110 1300 1310 1322 1322 1324 1322 1322 15 FIG. At block, the charger devicecauses an electrical current source to output a current to the transmit antenna coil to generate an EMF. In this example, the processoroutputs a signal to the current sourceto activate the current sourceto cause it to output an AC current to the transmit antenna coil. The current sourcein this example is a switching power amplifier, such as the example shown in. The current sourceoutputs the AC current at a predetermined frequency and with a predetermined default amount of current.

2120 1310 1330 1310 1333 1330 1331 1320 1333 1333 1331 1333 1333 1333 At block, the processorreceives one or more signals from the EMF sensor. In this example, the processorreceives a magnitude signal from the peak detectorthat indicates a peak magnitude of a received EMF. As discussed above the EMF sensoremploys a receive antenna coilto receive electrical energy from the EMF generated by the wireless field driver. The received electrical energy is then communicated to the peak detector. The peak detectorreceives the signal from the receive antenna coiland outputs a signal indicating the maximum amplitude of the received EMF. It should be appreciated that the signal output by the peak detector in this example is an analog voltage signal, in some examples, the peak detectormay output a digital value indicating the maximum amplitude of the received EMF. For example, the peak detectormay employ an analog to digital converter to generate a digital representation of the maximum amplitude. The output of the peak detectorin some examples may be a DC signal, though it should be appreciated that the signal may change based on the strength of the EMF.

1310 1337 1339 1339 1322 1339 1322 1337 1335 1339 1322 1337 1310 In addition to the magnitude signal, in this example the processoralso receives a phase signal from the phase detector. The phase signal indicates a difference in phase between the received EMF and a reference signal. In this example, the reference signalis output at the same frequency and phase as the AC current output by the current source. In some examples, the reference signalmay be output by the current source. As discussed above, the phase detectorreceives a signal from the zero-crossing detector, e.g., a square wave, and a reference signal. If the reference signalis output by the current source, it may be converted into a square wave, if it is not initially output as one. Any phase shift in the received EMF will result in periods during which the voltages (or currents) of the two signals are not equal. The duration of these differences with respect to the frequency of the two signals indicates the amount of phase shift. The phase detectordetects these differences in values, e.g., using a comparator, and outputs a signal indicating the phase difference to the processor.

It should be appreciated that the phase detection functionality may be omitted in some examples. While phase information can be used for a variety of functionality, it may not be necessary to estimate the strength of the generated EMF and so may be omitted.

2130 1310 1310 1333 1310 1310 1222 At block, the processordetermines a strength of the generated EMF. In this example, the processorreceives the magnitude signal from the peak detectorand determines the strength of the generated EMF based on the magnitude signal. In this example, the processoremploys a lookup table that correlates peak signal values, e.g., voltage, with EMF strength. However, in some examples, the processormay calculate an estimated EMF strength based on the magnitude signal and a characterization of the wireless field generator, e.g., based on transmit antenna coil (e.g., number of turns), and an amount of current output by the current source, using Faraday's law.

2140 1310 1310 1337 1310 At block, the processordetermines a load impedance of the target device. In this example, the processordetermines the load impedance of the target device based on the phase difference output by the phase detector. In this example, the processoremploys a lookup table that associates phase shifts with load impedances.

2150 1310 1310 1330 1310 1320 14 FIG. At block, the processoradjusts the current source to adjust an amount of current output by the wireless field driver to adjust the strength of the generated EMF. For example, the processormay adjust the amount of current to maintain a power characteristic of the generated EMF based on feedback information from the EMF sensor. Such a power characteristic may be an amplitude of the generated EMF, a frequency of the generated EMF, a phase of the generated EMF, etc. Such power characteristics may further be maintained or adjusted based on load impedance measurements, changes in power requirements for a remote device, etc. For example, as discussed above with respect to, the processormay implement a PID controller (or other feedback control system) to adjust the output current of the wireless field driver.

2160 1310 1300 1310 1520 2140 15 FIG. 15 17 FIGS.- At block, the processoradjusts operational parameters for the current source. In this example, the charger deviceemploys a tunable switching power amplifier, such as the one depicted in. To adjust the operational parameters, the processormay adjust the output voltage of the DC power supply or a duty cycle of the PWM gate driverbased on the load impedance estimated at blockas discussed above with respect to.

1310 1310 1310 1310 In some examples the processormay adjust an output voltage or a duty cycle of the power amplifier to reduce power consumption. For example, the processormay cause the current source to output a constant current while adjusting the duty cycle of the PWM gate driver. The amount of power consumed by the current source may then be measured and provided to the processor. The processormay then vary the duty cycle across a range of values and determine a duty cycle that has a minimum power consumption for the tested duty cycles.

2170 1310 1310 1310 At block, the processormay detect one or more foreign objects. In one example, the processormay compare the estimated load impedance against one or more threshold values to determine if the load impedance is within an expected range, or above (or below) an expected value. If the estimated load impedance falls outside of the expected range or does not meet the expected threshold, the processormay determine that a foreign object is present and interfering with the generated EMF.

2180 1310 1310 1310 1310 1310 1300 1310 1310 15 FIG. At block, the processormay determine one or more voltage or current harmonics within the generated EMF. For example, the processormay implement a fast-Fourier transform to obtain a spectral representation of the EMF. The processormay then identify one or more peak frequencies within the spectral representation to identify one or more harmonics. Alternatively, the processormay implement, or may be in communication with, one or more bandpass filters set to isolate one or more pre-determined frequencies. The processormay then determine a strength of the signals output by the filter(s) and compare the strength of the signals to one or more thresholds to determine if a harmonic frequency is present. If one or more harmonics is detected, it may indicate that the charger deviceis causing harmful interference. Thus, the processormay reduce the strength of the generated EMF until the strength of the detected harmonics falls below a predetermined threshold. To reduce the strength of the generated EMF, the processormay implement a second PID controller (or other suitable feedback controller), similar to the example shown in; however, the error signal may be the strength of the harmonic(s) and the target signal may be the threshold maximum tolerable harmonic strength.

It should be appreciated that some harmonics, e.g., high-frequency harmonics in the gigahertz range, may not be measured directly. Instead, the processor may indirectly detect such harmonics based on the presence of lower-frequency harmonics, e.g., in the sub-100 MHz range. The processor may then determine an estimated magnitude of one or more high-frequency harmonics, or determine whether an estimated magnitude of the high-frequency harmonics likely exceed a threshold magnitude, e.g., based on the magnitude of the lower-frequency harmonics exceeding a threshold.

2170 In addition, the processor may detect whether such harmonics are present, e.g., by detecting a threshold power level at one or more predetermined harmonic frequencies, and then, based on a lack of such harmonics in conjunction with a threshold amount of phase shift, may determine that a foreign object is present, as a continuation of the functionality discussed above with respect to block.

2190 1310 1337 1310 1310 1310 At block, the processormay obtain information output by the target device. For example, as discussed above, the target device may modulate its load impedance by activating and deactivating electronic functionality to transmit digital data via the generated EMF. Such changes in load impedance may be detected by the phase detector. By detecting changes between two different load impedances, the processormay detect binary values output at a pre-determined bit rate. For example, if the target device modulates its load impedance once per millisecond, the processormay sample the phase information once per millisecond to obtain a single bit. For example, if the phase shifts between two values, one value may represent a binary “1” and the other may represent a binary “0.” Thus, the processormay obtain a series of such binary values to obtain feedback information from the target device, e.g., an expected power requirement, a battery power level, etc.

21 FIG. 21 FIG. 2130 2190 1310 2140 2140 2160 2190 2130 2150 While the method ofwas described as including certain features being performed in a particular order, it should be appreciated that any of blocks-may be performed in any suitable order. For example, the processormay determine load impedance at blockbefore determining the strength of the EMF. Similarly, one or more blocks shown inare option. For example, one or more of blocksand-may be omitted in some examples. In some examples, blocksandmay be omitted. Thus, different examples methods may provide different functionality relating to control of the EMF, information about the status of a target device, information about nearby foreign objects, or harmful EMI.

22 FIG. 22 FIG. 15 FIG. Referring now to,provides a method for controlling a power amplifier, such as a power amplifier shown in. Though it should be appreciated that any suitable power amplifier may be employed.

2210 1570 2260 1570 2260 1570 At block, the controllerreceives an indication of load impedance from the impedance sensor. In this example, the controllerreceives a voltage signal from the impedance sensorcorresponding to a load impedance. However, in some examples, the controllermay receive a current signal, PWM signal, or a digital value indicating a load impedance. Still any other suitable impedance sensor may be employed.

2220 1570 1570 1570 11 11 FIGS.A-B At block, the controllerdetermines a duty cycle based on the load impedance. In this example, the controlleraccesses a look-up table stored in memory and determines a duty cycle corresponding to the load impedance. However, in some examples, the controllermay determine a duty cycle based on the load impedance and a mapping function stored in memory. For example a mapping function may comprise one or more polynomial functions mapping load impedance to duty cycle, such as described above with respect to.

2230 1570 1570 11 11 FIGS.A-B At block, the controllerdetermines a power supply voltage based on the determined duty cycle. In this example, the controlleraccesses a look-up table and determines a power supply voltage corresponding to the determined duty cycle. However, in some examples, the controller may determine a power supply voltage based on the duty cycle and a mapping function. For example a mapping function may comprise one or more polynomial functions mapping duty cycle to power supply voltage, such as described above with respect to.

2240 1570 1510 At block, the controllertransmits a signal to the DC/DC converterto adjust its output voltage based on the determined power supply voltage. In this example, the signal is a voltage signal indicating the determined power supply voltage; however, any suitable signal may be provided, including a current signal, a digital value indicating an output voltage selection, a PWM signal, etc.

2250 1570 1530 1570 1520 1570 At block, the controllertransmits the determined duty cycle to the power amplifier. In this example, the controllertransmits a voltage signal to a PWM gate controller, such as the PWM gate controller, to establish the determined duty cycle. Other suitable signals may be employed according to different examples, such as current signals, digital values, etc. In some examples, the controller comprises a processor having an integrated PWM circuit, and thus, the controllermay adjust an output duty cycle of the PWM circuit to provide a PWM signal.

2260 1530 7 1550 At block, the power amplifieroutputs a power signal to the transmit coil Lusing the impedance transformation networkbased on the determined duty cycle.

2200 2240 2250 22 FIG. It should be appreciated that while the methodofis described in a particular order, other orderings may be possible. For example, blocksandmay be reversed according to some examples, or may occur substantially simultaneously.

23 FIG. 23 FIG. 21 23 FIGS.- 11 11 3 FIGS.A,B, and 2300 2300 2310 2320 2300 2302 2310 2320 1000 2200 2350 2300 2340 2300 2360 2370 Referring now to,shows an example charger devicesuitable for use in example systems or methods for dynamic control of near-field wireless power according to this disclosure. The example computing deviceincludes a processorwhich is in communication with the memoryand other components of the computing deviceusing one or more communications buses. The processoris configured to execute processor-executable instructions stored in the memoryto perform one or more methods for dynamic control of near-field wireless power according to different examples, such as part or all of the example methodsanddescribed above with respect to. The computing device, in this example, also includes one or more user input devices, such as a keyboard, mouse, touchscreen, microphone, buttons, etc., to accept user input. The computing devicealso includes a displayto provide visual output to a user. Further, as discussed above with respect to, the charger devicealso includes a wireless field driverand an EMF sensor.

2300 2330 2330 The computing devicealso includes a communications interface. In some examples, the communications interfacemay enable communications using one or more communication techniques, such as BT or BLE, or using one or more communication networks, including a local area network (“LAN”); wide area network (“WAN”), such as the Internet; metropolitan area network (“MAN”); point-to-point or peer-to-peer connection; etc. Communication with other devices may be accomplished using any suitable networking protocol. For example, one suitable networking protocol may include the Internet Protocol (“IP”), Transmission Control Protocol (“TCP”), User Datagram Protocol (“UDP”), or combinations thereof, such as TCP/IP or UDP/IP.

While some examples of methods and systems herein are described in terms of software executing on various machines, the methods and systems may also be implemented as specifically-configured hardware, such as field-programmable gate array (FPGA) specifically to execute the various methods according to this disclosure. For example, examples can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in a combination thereof. In one example, a device may include a processor or processors. The processor comprises a computer-readable medium, such as a random access memory (RAM) coupled to the processor. The processor executes computer-executable program instructions stored in memory, such as executing one or more computer programs. Such processors may comprise a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), field programmable gate arrays (FPGAs), and state machines. Such processors may further comprise programmable electronic devices such as PLCs, programmable interrupt controllers (PICs), programmable logic devices (PLDs), programmable read-only memories (PROMs), electronically programmable read-only memories (EPROMs or EEPROMs), or other similar devices.

Such processors may comprise, or may be in communication with, media, for example one or more non-transitory computer-readable media, that may store processor-executable instructions that, when executed by the processor, can cause the processor to perform methods according to this disclosure as carried out, or assisted, by a processor. Examples of non-transitory computer-readable medium may include, but are not limited to, an electronic, optical, magnetic, or other storage device capable of providing a processor, such as the processor in a web server, with processor-executable instructions. Other examples of non-transitory computer-readable media include, but are not limited to, a floppy disk, CD-ROM, magnetic disk, memory chip, ROM, RAM, ASIC, configured processor, all optical media, all magnetic tape or other magnetic media, or any other medium from which a computer processor can read. The processor, and the processing, described may be in one or more structures, and may be dispersed through one or more structures. The processor may comprise code to carry out methods (or parts of methods) according to this disclosure.

The foregoing description of some examples has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications and adaptations thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure.

Reference herein to an example or implementation means that a particular feature, structure, operation, or other characteristic described in connection with the example may be included in at least one implementation of the disclosure. The disclosure is not restricted to the particular examples or implementations described as such. The appearance of the phrases “in one example,” “in an example,” “in one implementation,” or “in an implementation,” or variations of the same in various places in the specification does not necessarily refer to the same example or implementation. Any particular feature, structure, operation, or other characteristic described in this specification in relation to one example or implementation may be combined with other features, structures, operations, or other characteristics described in respect of any other example or implementation.

Use herein of the word “or” is intended to cover inclusive and exclusive OR conditions. In other words, A or B or C includes any or all of the following alternative combinations as appropriate for a particular usage: A alone; B alone; C alone; A and B only; A and C only; B and C only; and A and B and C.